Liquid crystal display device and method of fabricating same

ABSTRACT

A liquid crystal display device is provided that comprises a gate line; a first insulating film on the gate line; a data line crossing the gate line to define a pixel region, the pixel region having a transmissive area and a reflective area; a thin film transistor connected to the gate line and the data line; a pixel electrode formed in the pixel region; a second insulating film on the thin film transistor; a storage capacitor including a storage upper electrode overlapping the gate line; a transmission hole exposing at least a portion of the pixel electrode, and a reflective electrode formed in the reflective area of the pixel region, the reflective electrode connecting the pixel electrode with thin film transistor and the storage upper electrode, wherein the gate line and the pixel electrode include a first transparent conductive layer.

This application is a divisional of U.S. patent application Ser. No.11/142,315, filed Jun. 2, 2005, which claims the benefit of the KoreanPatent Application No. P2004-041141, filed on Jun. 5, 2004, all of whichare hereby incorporated by reference for all purposes as if fully setforth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transflective liquid crystal displaydevice and method of fabricating same.

2. Description of the Related Art

Liquid crystal display devices are generally classified into two types:the transmissive type in which pictures are displayed using lightsupplied from a backlight unit, and the reflective type in whichpictures are displayed using light reflected from an external source,such as natural light. There is a problem that the power consumption ofa backlight unit is high in the transmissive type and the reflectivetype depends on the external light so as not to be able to display thepicture in a dark environment.

In order to resolve such a problem, a transflective liquid crystaldisplay device is on the rise, wherein the transflective liquid crystalcan be selected to be in a transmissive mode where the backlight unit isused or in a reflective mode where the external light is used. Thetransflective liquid crystal display device operates in the reflectivemode if the external light is sufficient and in the transmissive mode ifthe external light is not sufficient, thus it might be able to reducethe power consumption more than the transmissive liquid crystal displaydevice and it is not restricted by the external light, which isdifferent from the reflective liquid crystal display device.

Generally, a transflective liquid crystal display panel, as shown inFIG. 1, includes a color filter substrate and a thin film transistorsubstrate which are bonded together with a liquid crystal layer (notshown) between them, and a backlight unit arranged behind the thin filmtransistor substrate. Each pixel of the transflective liquid crystaldisplay panel is divided into a reflective area where a reflectiveelectrode 28 is formed, and a transmissive area where the reflectiveelectrode 28 is not formed.

The color filter substrate includes a black matrix (not shown) and acolor filter 54 formed on an upper substrate 52, and a common electrode56 and an alignment film (not shown) formed there over.

The thin film transistor substrate includes a gate line 4 and a dataline (not shown) formed on a lower substrate 2 that define each pixelarea; a thin film transistor connected to the gate line 4 and the dataline; a pixel electrode 32 formed at the pixel area and connected to thethin film transistor; and a reflective electrode 28 formed at areflective area of each pixel to overlap the pixel electrode.

The thin film transistor includes a gate electrode 6 connected to thegate line 4; a source electrode 16 connected to the data line; a drainelectrode 18 facing the source electrode 16; an active layer thatoverlaps the gate electrode 6 with a gate insulating film 8 therebetween to form a channel between the source and drain electrodes 16,18; and an ohmic contact layer 12 to cause the active layer 10 to be inohmic-contact with the source and drain electrodes 16 and 18. The thinfilm transistor responds to a scan signal of the gate line 4 to cause avideo signal on the data line to be charged and maintained in the pixelelectrode 32.

The reflective electrode 28 reflects an external light that is incidentthrough a color filter substrate, toward the color filter substrate. Thesurface of the organic film 24 formed under the reflective electrode 28has an embossed or raised shape, therefore the reflective electrode 28,which is formed on top of the organic film, also has an embossed shape.As a result, the reflection efficiency of the reflective electrode 28increases due to the dispersion effect of the embossed surface.

When a pixel signal is applied to the pixel electrode 32 through thethin film transistor, a potential difference between a common electrode56 and the pixel electrode 28 is generated. The potential differencecauses a liquid crystal having dielectric anisotropy to rotate, therebycontrolling the transmissivity of the light that runs through the liquidcrystal layer in both the reflective and transmissive areas, thus itsbrightness is changed in accordance with the video signal.

In this case, a transmission hole 36 is formed in a relatively thickorganic film 24 at a transmissive area so that the length of the lightpath going through the liquid crystal layer is the same in thereflective area as in the transmissive area. As a result, the length ofthe path RL that ambient light incident to the reflective area travelsis the same as the length of the path TL that transmitted light from thebacklight unit 60, thus the transmission efficiency is the same in boththe reflective and transmissive modes.

The thin film transistor substrate further includes a storage capacitorconnected to the pixel electrode 32 in order to stably maintain thevideo signal supplied to the pixel electrode 32. The storage capacitoris formed by having a storage upper electrode 20 overlap the gate line 4with a gate insulating film there between, wherein the storage upperelectrode 20 is connected to the pixel electrode 32. The ohmic contactlayer 12 and the active layer 10 further overlap under the storage upperelectrode 20 in the process.

The thin film transistor substrate further includes a first passivationfilm 22 between the thin film transistor and the organic film 24; asecond passivation film between the organic film 24 and the reflectiveelectrode 28; and a third passivation film 30 between the reflectiveelectrode 28 and the pixel electrode 32. Accordingly, the pixelelectrode 32 is connected to the drain electrode 18 and the storageupper electrode 20 through each of the first and second contact holes34, 38 that penetrate the first to third passivation films 22, 26, 30,an organic film 24 and the reflective electrode 28.

In such a transflective liquid crystal display panel, the thin filmtransistor substrate includes the semiconductor process and requires aplurality of mask processes, thus its manufacturing process iscomplicated so that it becomes a material cause for the increase of theliquid crystal display panel manufacturing cost. Hereinafter, afabricating method of the transflective thin film transistor substratewill be described in reference with FIGS. 2A to 2F.

Referring to FIG. 2A, a gate metal layer is formed on the lowersubstrate 2 using a deposition method such as sputtering. Subsequently,the gate metal layer is patterned with a first mask using aphotolithography process and an etching process, thereby forming thegate pattern including the gate line 4 and the gate electrode 8. Thegate metal layer is a single layered or double layered metal such as Al,Mo, Cr.

Next, the gate insulating film 8 is formed on the substrate 2 where thegate pattern is formed, and a source/drain pattern is formed on topthereof using a second mask process as illustrated in FIG. 2B Thesource/drain pattern includes the data line, the source electrode 16,the drain electrode 18 and the storage upper electrode 20.

The gate insulating film 8, an amorphous silicon layer 10, an amorphoussilicon layer with impurities doped thereto 12, and the source/drainmetal layer are sequentially formed on the lower substrate 2 where thegate pattern is formed. The gate insulating film 8 is an inorganicinsulating material such as silicon oxide SiOx or silicon nitride SiNx,and the source/drain metal layer is a single or double layered metalstructure such as Al, Mo and the like.

A photo resist pattern is formed on top of the source/drain metal layerusing a second mask and a photolithography process. During this process,a diffractive exposure mask with a diffractive exposure part at achannel part of the thin film transistor is used as the second mask,thus the photo resist pattern of the channel part is made to have alower height than the source/drain pattern part.

There after, the source/drain metal layer is patterned by wet etchingusing the photo resist pattern to form the source/drain pattern thatincludes the data line, the source electrode 16, the drain electrode 18integrated with the source electrode 16, and the storage upper electrode20.

Next, an amorphous silicon layer doped with the impurities and anamorphous silicon layer are simultaneously patterned by a dry etchingusing the same photo resist pattern, thereby forming the ohmic contactlayer 12 and the active layer 10.

After removing the photo resist pattern having relatively low height atthe channel part by ashing, the source/drain pattern and the ohmiccontact layer 12 of the channel part are dry etched. Accordingly, theactive part 10 of the channel part is exposed to separate the sourceelectrode 16 from the drain electrode 18. There after, the photo resistpattern remaining on the source/drain pattern is removed using a stripprocess.

Referring to FIG. 2C, a first passivation film 22 is formed on the gateinsulating film 8 where the source/drain pattern is formed, and anorganic film 24 is formed on top thereof using a third mask process,such that the organic film 24 has first and second initial contact holes34, 38 and a transmission hole 36 with an embossed shaped surface.

The first passivation film 22 and the organic film 24 are sequentiallyformed on the gate insulating film 8 where the source/drain pattern isformed. The first passivation film 22 is of the same inorganicinsulating material as the gate insulating film 8, and the organic film24 is of a photosensitive organic material such as acrylic resin.

Then, the organic film 24 is patterned using the third mask, therebyforming first and second open holes 35, 37 and the transmission hole 36which penetrate the organic film 24 in correspondence to thetransmissive part of the third mask. The third mask has a structurewhere a shielding part and a diffractive exposure part repeat at therest area except for the transmissive part. The organic film 24remaining in correspondence thereto is patterned to have a structurethat a shielding area (projected part) and a diffractive exposure area(groove part) having a stepped difference are repeated. Subsequently,the organic film 24 where the projected part and the groove part arerepeated is cured so that the surface of the organic film 24 has theembossed shape.

Referring to FIG. 2D, a second passivation film 26 is formed on theorganic film 24, and the reflective electrode 28 is formed on topthereof using a fourth mask process. The second passivation film 26 andthe reflective metal layer are deposited to maintain their embossedshape on top of the organic film 24 that has the same embossed surface.The second passivation film 26 is an inorganic insulating material suchas the first passivation film 22, and the reflective metal layer is ametal with high reflectivity such as AlNd.

Subsequently, the reflective metal layer is patterned using a fourthmask and etching process, thus the reflective electrode 28 is formed,wherein the reflective electrode is independent every pixel and isopened at the transmission hole 36 and the first and second open holes35, 37 of the organic film 24.

Referring to FIG. 2E, a third passivation film 30 covering thereflective electrode 28 is formed using a fifth mask process, and firstand second contact holes 34, 38 penetrating the first to thirdpassivation films 22, 26, 30 are formed. The third passivation film 30the reflective electrode 28 and the first and second contact holes 34,38 are formed with the fifth mask using photolithography and etchingprocesses, such that the first and second contact holes 34, 38 penetratethe first to third passivation films 22, 26, 30 at the first and secondopen holes 35, 37 of the organic film 24. The first and second contactholes 34, 38 each expose the drain electrode 18 and the storage upperelectrode 20. The third passivation film is of the same inorganicinsulating material as the second passivation film.

Referring to FIG. 2F, a pixel electrode 32 is formed on the thirdpassivation film 30 by use of a sixth mask process. More specifically, atransparent conductive layer is formed on the third passivation film 30using a deposition method such as sputtering, and the transparentconductive layer is patterned by the photolithography process using asixth mask and the etching process to form the pixel electrode at eachpixel area. The pixel electrode 32 is connected to the drain electrode18 and the storage upper electrode 20 through the first and secondcontact holes 34 and 38. The transparent conductive layer is of indiumtin oxide ITO.

Accordingly, the related art transflective thin film transistorsubstrate is formed using six 6 different mask processes, thus there isa disadvantage that its manufacturing process is complicated. Further,the margin of the first and second contact holes 34, 38 should besecured sufficiently in order for the pixel electrode 32 to be connectedto the drain electrode 18 and the storage upper electrode 20 in therelated art transflective thin film transistor substrate. Because ofthis, there is a disadvantage that the aperture ratio of thetransmissive area is reduced.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a transflective liquidcrystal display device and method of manufacturing same that thatsubstantially obviates one or more of the problems due to limitationsand disadvantages of the related art.

Accordingly, an advantage of the present invention is to provide atransflective thin film transistor substrate with increased apertureratio in a transmissive area, and a simplified method of fabricatingsame.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings

To achieve these and other advantages an in accordance with the purposeof the present invention, as embodied and broadly described, a liquidcrystal display device, comprising: a gate line; a first insulating filmon the gate line; a data line crossing the gate line to define a pixelregion, the pixel region having a transmissive area and a reflectivearea; a thin film transistor connected to the gate line and the dataline; a pixel electrode formed in the pixel region; a second insulatingfilm on the thin film transistor; a storage capacitor including astorage upper electrode overlapping the gate line; a transmission holeexposing at least a portion of the pixel electrode, and a reflectiveelectrode formed in the reflective area of the pixel region, thereflective electrode connecting the pixel electrode with thin filmtransistor and the storage upper electrode, wherein the gate line andthe pixel electrode include a first transparent conductive layer.

In another aspect of the present invention, a method of fabricating aliquid crystal display device is provided, comprising: forming a gatepattern including a first transparent conductive layer using a firstmask, the gate pattern including a pixel electrode, a gate electrode anda gate line; forming a first insulating film on the gate pattern;forming a semiconductor layer and a source/drain pattern on the firstinsulating film using a second mask, the source/drain pattern having astorage upper electrode, a drain electrode, a source electrode, and adata line; forming a second insulating film over the source/drainpattern having an aperture portion using a third mask; forming atransmission hole exposing the first transparent conductive layer of thepixel electrode using a fourth mask; and forming a reflective electrodein a reflective area using a fifth mask; the reflective electrodeconnecting the pixel electrode with the drain electrode and the storageupper electrode through the transmission hole.

In another aspect of the present invention, a method of fabricating aliquid crystal display device is provided, comprising: forming a gatepattern having a first transparent conductive layer and a second opaquesecond conductive layer using a first mask, the gate pattern including apixel electrode, a gate electrode and a gate line; forming a firstinsulating film and a semiconductor layer on the gate pattern, and asource/drain pattern having a storage upper electrode, a drainelectrode, a source electrode, a data line using a second mask; forminga transmission hole exposing the first conductive layer of the pixelelectrode in a transmission area using a third mask; forming a secondinsulating film over the source/drain pattern using a fourth mask; andforming a reflective electrode in a reflective area using a fifth mask,the reflective electrode connecting the pixel electrode with the drainelectrode and the storage electrode through the transmission hole.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a sectional diagram illustrating a part of a related arttransflective liquid crystal display panel;

FIGS. 2A to 2F are sectional diagrams illustrating a method offabricating a transflective thin film transistor substrate according tothe related art;

FIG. 3 is a plane view illustrating a transflective thin film transistorsubstrate according to an embodiment of the present invention;

FIG. 4 is a sectional diagram illustrating the transflective thin filmtransistor substrate shown in FIG. 3, taken along the line II-II′,III-III, IV-IV′;

FIGS. 5A and 5B illustrate a plane view and a sectional diagram,respectively, of a first mask process according to an embodiment of thepresent invention;

FIGS. 6A and 6B illustrate a plane view and a sectional diagram,respectively, of a second mask process according to an embodiment of thepresent invention;

FIGS. 7A to 7E are sectional diagrams further illustrating a second maskprocess of the present invention;

FIGS. 8A and 8B illustrate a plane view and a sectional diagram,respectively, of a third mask process according to an embodiment of thepresent invention;

FIGS. 9A and 9B illustrate a plane view and a sectional diagram,respectively, of a fourth mask process according to an embodiment of thepresent invention;

FIGS. 10A and 10B illustrate a plane view and a sectional diagram,respectively, of a fifth mask process according to an embodiment of thepresent invention;

FIG. 11 is a plane view illustrating the transflective thin filmtransistor substrate according to the present invention, with asurrounding part centered;

FIG. 12 is a plane view illustrating a static electricity preventiondevice area and a contact area of a data link and a data line shown inFIG. 11;

FIG. 13 is sectional diagram illustrating the transflective thin filmtransistor substrate shown in FIG. 12, taken along the line V-V′ andVI-VI′;

FIGS. 14A and 14B illustrate a plane view and a sectional diagram,respectively, of a first mask process according to another embodiment ofthe invention;

FIGS. 15A and 15B illustrate a plane view and a sectional diagram,respectively, of a second mask process according to the other embodimentof the invention;

FIGS. 16A and 16B illustrate a plane view and a sectional diagram,respectively, of a third mask process according to the other embodimentof the invention;

FIGS. 17A and 17B illustrate a plane view and a sectional diagram,respectively, of a fourth mask process according to the other embodimentof the invention;

FIGS. 18A and 18B illustrate a plane view and a sectional diagram,respectively, of a fifth mask process according to the other embodimentof the invention;

FIG. 19 is a sectional diagram illustrating the thin film transistorsubstrate according to another embodiment of the present invention;

FIG. 20 is a sectional diagram illustrating the thin film transistorsubstrate according to another embodiment of the present invention; and

FIGS. 21A to 21E are sectional diagrams illustrating a method offabricating of the transflective thin film transistor substrateillustrated in FIG. 20.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 3 is a plane view illustrating a transflective thin film transistorsubstrate according to the present invention, and FIG. 4 is a sectionaldiagram illustrating the transflective thin film transistor substrateillustrated in FIG. 3, taken along the line II-II′, III-III′, IV-IV′.

Referring to FIGS. 3 and 4, the transflective thin film transistorsubstrate includes a gate line 102 and a data line 104 that define apixel area on a lower substrate 142 by crossing each other with a gateinsulating film 144 there between; a thin film transistor 106 connectedto the gate line 102 and the data line 104; a reflective electrode 152formed in a reflective area of each pixel; and a pixel electrode 118formed at each pixel area and connected to the thin film transistor 106through the reflective electrode 152. The transflective thin filmtransistor substrate also includes a storage capacitor 120 that isformed by the overlapping of the previous stage gate line 102 and astorage upper electrode 122 connected to a pixel electrode 118 through areflective electrode 152; a gate pad 128 connected to the gate line 102;and a data pad 138 connected to the data line 104. The transflectivethin film transistor substrate divides each pixel area into a reflectivearea where the reflective electrode 152 is formed and a transmissivearea where the reflective electrode 152 is not formed.

The thin film transistor 106 includes a gate electrode 108 connected tothe gate line 102; a source electrode 110 connected to the data line104; a drain electrode 112 facing the source electrode 110 to beconnected to the pixel electrode 118; an active layer 114 that overlapsthe gate electrode 108 with a gate insulating film 144 therebetween toform a channel between the source electrode 110 and the drain electrodes112; and an ohmic contact layer 116 formed on the active layer 114except for a channel part so as to be in ohmic-contact with the sourceelectrode 110 and the drain electrodes 112.

The thin film transistor 106 responds to a scan signal on the gate line102 to cause a video signal on the data line 104 to be charged andmaintained in the pixel electrode 118.

As illustrated in FIG. 4, the gate line 102 and the gate electrode 108have a double layer structure including a first transparent conductivelayer 101 and a second conductive metal layer 103 deposited on top ofthereof. A semiconductor pattern 115 including the active layer 114 andthe ohmic contact layer 116 is formed such that it overlaps the dataline 104.

The reflective electrode 152 is formed in the reflective area of eachpixel to reflect external light. The reflective electrode 152 has anembossed shape corresponding to the shape of the second passivation film150 and the organic film 148 there under. The embossed shape of thereflective electrode increases its reflection efficiency due to thedispersion effect.

The pixel electrode 118 is formed at each pixel area and connected tothe drain electrode 112 through the reflective electrode 152 that goesthrough an edge part of a transmission hole 154. The pixel electrode 118has a double structure that the first and second conductive layers 101,103 are formed like the gate line 102, and it is opened through thetransmission hole 154 to make the first conductive layer 101 being thetransparent conductive layer exposed to the transmissive area.

The pixel electrode 118 generates a potential difference with a commonelectrode of a color filter substrate (not shown) by the pixel signalsupplied through the thin film transistor. The potential differencecauses a liquid crystal having dielectric anisotropy to rotate, therebycontrolling the transmissivity of the light that runs through a liquidcrystal layer of each of the reflective area and the transmissive area,thus its brightness is changed in accordance with the video signal.

The transmission hole 154 is formed in the transmissive area topenetrate a gate insulating film 144 on the pixel electrode 118, and afirst passivation film 146, an organic film 148 and a second passivationfilm 150 on the thin film transistor 106. Accordingly, the length of thelight path that runs through the liquid crystal layer is the same in thereflective area and the transmissive area, thus the transmissionefficiency of the reflective mode and the transmissive mode is the same.

The storage upper electrode 122 connected to the pixel electrode 118overlaps the previous gate line 102 with the gate insulating film 144therebetween, thereby forming the storage capacitor 120. The storageupper electrode 122 is connected to the pixel electrode 118 through thereflective electrode 152 that runs through the edge part of thetransmission hole 154, and it further overlaps the semiconductor pattern115 under the storage upper electrode 122.

The gate line 102 is connected to a gate driver (not shown) through thegate pad 128. The first and second conductive layers 101, 103 of thegate line 102 are extended to form the gate pad 128, and the firstconductive layer 101 is exposed through a first contact hole 130 thatpenetrates from the second passivation film 150 to the second conductivelayer 103.

The data line 104 is connected to a data driver (not shown) through thedata pad 138. The data pad 138 has a double structure that the first andsecond conductive layers 101, 103 are formed like the gate pad 128, andthe first conductive layer 101 is exposed through the second contacthole 140 that penetrates from the second passivation film 150 to thesecond conductive layer 103. The data pad 138 is connected to the dataline 104 through a separate contact electrode (not shown).

In this way, the transflective thin film transistor substrate accordingto this embodiment of the present invention has the pixel electrode 118connected to the drain electrode 112 and the storage upper electrode 122through the reflective electrode that runs through the edge part of thetransmission hole 154. Accordingly, it is not necessary to have aseparate contact hole for connecting the pixel electrode 118 with thedrain electrode 112 and the storage upper electrode 122, thus theaperture ratio of the transmissive area can be increased as much.

The reflective electrode 152 is also connected to the first and secondconductive layers 101, 103 of the pixel electrode 118. Accordingly, AlNdand ITO are connected through Mo in case that AlNd is used for thereflective electrode 152, ITO is used for the first conductive layer 101of the pixel electrode 118 and Mo is used for the second conductivelayer 103, thus the contact resistance of AlNd and ITO caused by thegeneration of Al2O3 might be able to be reduced.

FIGS. 5A and 5B illustrate a plane view and a sectional diagramrespectively, of a first mask process according to an embodiment of thepresent invention. First, a gate pattern having a double layeredstructured is formed using a first mask (not shown), wherein the gatepattern includes a pixel electrode 118, a data pad 138, a gate electrode108 connected to the gate line 102 and a gate line 102 on a lowersubstrate 142. The double layered structure includes first and secondconductive layers 101, 103.

Specifically, the first and second conductive layers 101, 103 are formedon the lower substrate 102 using a deposition method such as sputtering.Then the first and second conductive layers 101, 103 are patterned usinga first mask formed using a photolithography process and etchingprocess, thereby forming the gate pattern illustrated in FIGS. 5A and5B. The gate pattern includes the gate line 102, the gate electrode 108,the gate pad 128, the data pad 138, the pixel electrode 118. The firstconductive layer 101 is a transparent conductive material such as ITO,TO, IZO, and the second conductive layer 103 is a metal material such asMo, Ti, Cu, Al(Nd) and the like.

FIGS. 6A and 6B illustrate a plane view and a sectional diagram,respectively, of a second mask process according to an embodiment of thepresent invention. Referring to FIG. 6B, a gate insulating film 144 isformed on the lower substrate 142 where the gate pattern has beenformed. Then, utilizing a second mask process, a source/drain patternincluding a data line 104, a source electrode 110, a drain electrode112, and a storage upper electrode 122, and a semiconductor pattern 115including an active layer 114 and an ohmic contact layer 116 thatoverlap along the rear surface of the source/drain pattern are formed ontop thereof. The semiconductor pattern 115 and the source/drain patternare formed using a single mask process by utilizing a diffractiveexposure mask.

Referring to FIG. 7A, first a gate insulating film 144, an amorphoussilicon layer 105, an amorphous silicon layer 107 doped with impuritiesn+ or p+, and a source/drain metal layer 109 are sequentially formed onthe lower substrate 142 over the gate pattern. For example, the gateinsulating film 144, the amorphous silicon layer 105, the amorphoussilicon layer 107 doped with impurities are formed using PECVD, and thesource/drain metal layer 109 is formed using sputtering. The gateinsulating film 144 is an inorganic insulating material such as siliconoxide SiOx, silicon nitride SiNx, and the source/drain metal layer 109is Cr, Mo, MoW, Al/Cr, Cu, Al(Nd), Al/Mo, Al(Nd)/Al, Al(Nd)/Cr,Mo/Al(NdO/Mo, Cu/Mo, Ti/Al(Nd)/Ti or the like. When the double layeredstructure is Al/Cr, the Al layer is formed after the Cr layer.

A photo resist 219 is spread over the source/drain metal layer 109, andthen exposed and developed using a diffractive exposure mask 210. Thediffractive exposure mask 210 includes a transparent quartz substrate212, a shielding layer 214 formed of a metal layer such as Cr on topthereof, and a diffractive exposure slit 216. The shielding layer 214 islocated at an area where the semiconductor pattern and the source/drainpattern is to be formed. The diffractive exposure slit 216 is located atan area where the channel of the thin film transistor is to be formed.Accordingly, after development a photo resist pattern 220 having thestepped structure illustrated in FIG. 7B is formed.

Referring to FIG. 7B, the shielding layer 214 intercepts ultra violetrays during processing, thereby leaving a first resist pattern 220A. Thediffractive exposure slit 216 diffracts the ultra-violet rays duringprocessing thereby leaving a second photo resist pattern 220B that isthinner than the first photo resist pattern 220A.

The source/drain metal layer 109 is then etched using the photo resistpattern 220 to form a source/drain pattern and the semiconductor pattern115 as illustrated in FIG. 7C. At this point in the process, the sourceelectrode 110 and the drain electrode 112 are integrated within thesource/drain pattern i.e., there is not break between the source anddrain electrode.

Next, the photo resist pattern 220 is ashed using oxygen O2 plasma.Because of the thickness of the first photo resist pattern 220A thelayers under the first photo resist pattern remains unchanged, i.e.,only the thickness of the photo resist is thinned. However, the layersunder the second photo resist pattern 220B which was thinner, areremoved during the etching process, thereby separating the sourceelectrode 110 from the drain electrode 112 and exposing the active layer114 as illustrated in FIG. 7D. Accordingly, a channel is formed in theactive layer 114 between the source electrode 110 and the drainelectrode 112. In addition, both sides of the source/drain pattern areetched once more along the ashed first photo resist pattern 220A, thusthe source/drain pattern and the semiconductor pattern 115 have a fixedstepped difference in a step shape. The first photo resist pattern 220Aremaining on the source/drain pattern is removed by a strip process asin FIG. 7E.

FIGS. 8A and 8B illustrate a plane view and a sectional diagram,respectively, of a third mask process utilized to fabricate atransflective thin film transistor substrate according to an embodimentof the present invention. Referring to FIGS. 8A and 8B, a firstpassivation film 146 is formed on the surface of the thin filmtransistor substrate including the area where the source/drain patternis formed using for example, a deposition method such as sputtering.Then an organic film 148 is formed on top thereof using for example spincoating and is then patterned using a third mask process, such that theorganic film 148 has an aperture part 155 in the transmissive area andan embossed surface in the reflective area.

The first passivation film 146 is an inorganic insulating material suchas the gate insulating film 144 and the organic film 148 is aphotosensitive organic material such as acrylic resin. The organic film148 is patterned using the third mask such that the aperture part 155penetrating the organic film 148 is formed in the transmissive area incorrespondence with the transmissive part of the third mask, and theorganic film 148 of the pad area where the gate pad 128 and the data pad138 are formed is removed. Further, the remaining part except for thetransmission part in the third mask has a structure that the shieldingpart and the diffractive exposure part (or transflective part) arerepeated, in correspondence thereto, the organic film 148 is patternedto have a structure where the shielding area (projected part) and thediffractive exposure area (groove part) having the stepped differenceare repeated in the reflective area. Subsequently, the organic film 148with the repeated projected part and groove part is fired to form anembossed shape on the surface of the organic film 148 in the reflectivearea. On the other hand, the aperture part 155 of the organic film 148has its edge part overlap the drain electrode 112 and the storage upperelectrode 122, thereby making the edge part of the storage upperelectrode 122 and the drain electrode 112 projected toward the aperturepart 155.

FIGS. 9A and 9B illustrate a plane view and a sectional diagram,respectively, of a fourth mask process utilized to fabricate atransflective thin film transistor substrate according to an embodimentof the present invention. Referring to FIG. 9B, a second passivationfilm 150 having an embossed shape is formed on the organic film 148using the fourth mask process, and first and second contact holes 130,140 and the transmission hole penetrating from the second passivationfilm 150 to the second conductive layer 103 of the gate pattern areformed.

Specifically, the second passivation film 150 is formed on the organicfilm 148 using a deposition method such as PECVD. The second passivationfilm 150 is of the same inorganic insulating material as the firstpassivation film 146. Subsequently, the transmission hole 154 is formedin the transmissive area of each pixel where the aperture part 155 ofthe organic film 148 is formed and first and second contact holes 130,140 are formed at the pad areas. The transmission hole 154 penetratesthe second passivation film 150, the first passivation film 146, thegate insulating film 144 and the second conductive layer 103 of thepixel electrode 118 in the aperture part 155 of the organic film 148.Accordingly, the first conductive layer 101 of the pixel electrode 118is exposed through the transmission hole 154, and the second conductivelayer 103 remains only at the border of the pixel electrode, where thefirst conductive layer 101 is unexposed. Further, the drain electrode112 projected toward the aperture part 155 of the organic film 148through the edge part of the transmission hole 154, and the edge part ofthe storage upper electrode 122 are exposed. The first and secondcontact holes 130, 140 penetrate from the second passivation film 150 tothe second conductive layer 103 of the gate pad 128 and the data pad 138on top of the gate pad 128, the data pad 138 respectively. Accordingly,the first conductive layer 101 of the gate pad 128 and the data pad 138is exposed through each of the first and second contact holes 130, 140,and the second conductive layer 103 remains only at the border where thefirst conductive layer 101 is unexposed.

FIGS. 10A and 10B illustrate a plane view and a sectional diagram,respectively, of a fifth mask process utilized to fabricate atransflective thin film transistor substrate according to an embodimentof the present invention. Referring to FIG. 10B, a reflective metallayer is formed on the second passivation film 150 maintaining theembossed shape. The reflective metal layer is a metal that has highreflectivity, for example, AlNd. There after, the reflective metal layeris patterned by the photolithography process using the fifth mask and anetching process, thereby forming the reflective electrode 152 in thereflective area of each pixel. The reflective electrode 152 connects thedrain electrode 112 with the pixel electrode 118 through the edge partof the transmission hole 154, and connects the storage upper electrode122 with the pixel electrode 118. Accordingly, no separate contact holeis required for connecting the pixel electrode 122 with the drainelectrode 112 and the storage upper electrode 122, thus the apertureratio of the transmissive area is increased. Furthermore, the reflectiveelectrode 152 is connected to the first conductive layer 101 of thepixel electrode 118 and to the edge part of the second conductive layer103 Mo exposed through the edge part of the transmission hole 154, thusthe contact resistance of the reflective electrode 152 AlNd and thefirst conductive layer 101 ITO is reduced.

The transflective thin film transistor substrate according to thepresent invention connects the pixel electrode 118 with the drainelectrode 112 and the storage upper electrode 122 using of thereflective electrode 152, and reduces the fabrication process to a fivemask process. In contrast to the related art which requires a six maskprocess.

FIG. 11 illustrates the ambient part of the transflective thin filmtransistor substrate according to an embodiment of the presentinvention.

The transflective thin film transistor substrate 100 shown in FIG. 11includes a contact electrode 160 in order to connect the data pad 138formed in the same layer as the gate pad 128 with the data line 104. Inother words, the contact electrode 160 connects a data link 136 extendedfrom the data pad 138 with the data line 104. Herein, the contactelectrode 160 is formed of the same metal layer AlNd, AlNd/Mo as thereflective electrode 152 that is formed at the active area. The contactelectrode 160 has a problem that it is corroded by oxidization when itis exposed to the outside, thus it is located at an area which is sealedby a sealant 180, i.e., between the sealant 180 and an active area 182.

Further, the thin film transistor substrate 100 includes a electrostaticdischarging device 190 for intercepting static electricity flowing intothe active area 182. The electrostatic discharging device 190 isconnected to the data line 104 or the gate line 102, and composed of aplurality of thin film transistors 300, 310, 320 having a reciprocalconnection relationship. The electrostatic discharging device 190 causesany over current to be discharged by having low impedance at a highvoltage area by the static electricity, thereby intercepting the staticelectricity inflow. It does not affect a drive signal supplied throughthe gate line 102 or the data line 104 by having high impedance furing anormal drive environment. The electrostatic discharging device 190requires a plurality of contact electrodes for reciprocally connectingthe thin film transistors 300, 310, 320. The contact electrodes are alsoformed of the same metal layer AlNd, AlNd/Mo as the reflective electrode152. Accordingly, the electrostatic discharging device 190 is alsoformed at the area sealed by the sealant 180, i.e., between the sealant180 and the active area 182.

FIG. 12 is a plane view illustrating the electrostatic dischargingdevice 190 and the contact electrode 160 connected to the data line 104shown in FIG. 11. Referring to FIG. 12, the data line 104 is connectedto a data line 136 extended from the data pad 138 through a firstcontact electrode 160 in an area which is to be sealed by the sealant180. The data link 136 has a double structure including first and secondconductive layers 101, 103 formed like the data pad 138 (discussedabove). The first contact electrode 160 is connected to the data line104 side by side through a third contact hole 162 that penetrates fromthe second passivation film 150 to the data line 104 and thesemiconductor pattern 115. Further, the contact electrode 160 isconnected to the data link 136 through a fourth contact hole 164 thatpenetrates from the second passivation film 150 to the second conductivelayer 103 of the data link 136, as illustrated in FIG. 13.

The electrostatic discharging device connected to the data line 104includes thin film transistors 300, 310, 320. The second thin filmtransistor 300 includes a second source electrode 304 connected to thedata line 104, a second drain electrode opposite the second sourceelectrode 304, and a second gate electrode 302 having a double layeredstructure overlapping the second source and drain electrodes 304, 306with the semiconductor pattern 115 and the gate insulating film 144there between. The double structure of the second gate electrode 302includes first and second conductive layers 101, 103.

The third thin film transistor 310 is connected to the second sourceelectrode 304 and the second gate electrode 302 of the second thin filmtransistor in a diode form. The third thin film transistor 310 includesa third source electrode 314 connected to the second source electrode304, a third drain electrode 316 opposite the third source electrode314, and a third gate electrode 312 overlapping the third source anddrain electrodes 314, 316 with the semiconductor pattern 115 and thegate insulating film 144 there between. The third gate electrode 312,like the second, has a double layered structure including first andsecond conductive layers 101, 103. The third gate electrode 312 is alsoconnected to the third source electrode 314 through the second contactelectrode 332. In other words, the third contact electrode 332 is formedto lay from a fifth contact hole 340 that penetrates from the secondpassivation film 150 to the third drain electrode 316 and thesemiconductor pattern 115, and a sixth contact hole that penetrates fromthe second passivation film 150 to the second conductive layer 103 ofthe third gate electrode 312, thereby connecting the third drainelectrode 316 with the third gate electrode 312.

The fourth thin film transistor 320 is connected to the second drainelectrode 306 and the second gate electrode 302 of the second thin filmtransistor in a diode form. The fourth thin film transistor 320 includesa fourth source electrode 324 connected to the second drain electrode306, a fourth drain electrode 326 opposite the fourth source electrode324, and a fourth gate electrode 322 overlapping the fourth source anddrain electrodes 324, 326 with the semiconductor pattern 115 and thegate insulating film 144 there between. The fourth gate electrode 322has a double layered structure including first and second conductivelayers 101, 103. The fourth drain electrode 326 is also connected to thethird drain electrode 316, and it is connected to the second gateelectrode 302 through the third contact electrode 334 which is formed tolay over a seventh contact hole 344 and an eighth contact hole 346.Further, the fourth gate electrode 332 is connected to the fourth sourceelectrode 324 through the fourth contact electrode 336 which is formedto lay over a ninth contact hole 348 and a tenth contact hole 350.

The first to fourth contact electrodes 160, 332, 334, 336 are formed ofthe same metal layer as the reflective electrode 152 as described above.

The transflective thin film transistor substrate having such a structureis formed using five mask processes as described above. This will beexplained with reference to FIGS. 14A to 18B.

Referring to FIGS. 14A and 14B, a gate pattern is formed on the lowersubstrate 142 by a first mask process, wherein the gate pattern includesthe data link 136 along with the data pad 138, and the second to fourthgate electrodes 302, 312, 322. The first mask process is the same asdescribed in FIGS. 5A and 5B.

Then as illustrated in FIGS. 15A and 15B, a gate insulating film 144, asemiconductor pattern 115 including an active layer 114 and an ohmiccontact layer 116, and a source/drain pattern including a data line 104,second to fourth source electrodes 304, 314, 324, second to fourth drainelectrodes 306, 316, 326 are formed using a second mask process. Thesecond mask process is the same as described in FIGS. 6A and 7E.

A first passivation film 146 and an organic film 148 on top thereof, arethen formed, and the organic film 148 is patterned using a third maskprocess. As illustrated in FIG. 16B, the organic film 148 has third totenth aperture parts 161, 163, 339, 341, 343, 345, 347, 349. The thirdmask process is the same as described in FIGS. 8A and 8B. In this case,the organic film is removed in the pad area and does not have theembossed surface at an area where the reflective electrode 152 is notformed, e.g., the pixel area.

Referring to FIGS. 17A and 17B, a second passivation film 150 is formedusing a fourth mask process, and third to tenth contact holes 162, 164,340, 342, 344, 346, 348, 350 are formed to overlap the third to tenthaperture parts 161, 163, 339, 341, 343, 345, 347, 349 of the organicfilm 148. The fourth mask process is the same as described in FIGS. 9Aand 9B.

Referring to FIGS. 18A and 18B, first to fourth contact electrodes 160,332, 334, 336 are formed of the same metal as the foregoing reflectiveelectrode 152 using a fifth mask process. The fifth mask process is thesame as described in FIGS. 10A and 10B.

FIG. 19 is a sectional diagram illustrating a pixel area along the lineII-II′ and a contact area of a data link 136 and a data line 104 alongthe line V-V′ in a transflective thin film transistor substrateaccording to the second embodiment of the present invention.

The transflective thin film transistor substrate shown in FIG. 19includes the same components as the transflective thin film transistorsubstrate shown in FIGS. 4 and 13 except that the reflective electrode252 and the first contact electrode 262 are formed in a double structureof the first and second conductive layers 254, 256. Accordingly,explanation for the repeated components is to be omitted.

The first conductive layer 254 in the reflective electrode 252 and thefirst contact electrode 262 illustrated in FIG. 19 is the transparentfirst conductive layer 101 of the data link 136 and the pixel electrode118, which has low contact resistance, such as Mo. And the secondconductive layer 256 is of a metal which has high reflexibility such asAlNd. Accordingly, the second conductive layer 256 AlNd of the firstcontact electrode 262 and the reflective electrode 252 are directlyconnected to the first conductive layer 101 ITO of the data link 136 andthe pixel electrode 118, thus generation of an Al2O3 layer is prevented.Accordingly, the contact resistance of the reflective electrode 252 andthe pixel electrode 118, and the contact resistance of the first contactelectrode 160 and the data link 136 are reduced.

FIG. 20 is a sectional diagram illustrating a pixel area along the lineII-II′ and a contact area of a data link 136 and a data line 104 alongthe line V-V′ in a transflective thin film transistor substrateaccording to a third embodiment of the present invention.

The transflective thin film transistor substrate shown in FIG. 20includes the same components as the transflective thin film transistorsubstrate shown in FIGS. 4 and 13 except that the second passivationfilm 150 on the organic film 148 is removed. Accordingly, explanationfor the repeated components is to be omitted.

The second passivation film 150 illustrated in FIGS. 4 and 13 reinforcesthe adhesive strength of the organic film 148 and the reflectiveelectrode 152, but can be omitted. Referring to FIG. 20, the secondpassivation film 150 is omitted, the transmission hole 154 and the firstto fourth contact holes 130, 140, 162, 164 are formed in the firstpassivation film 146 process before the organic film 148 is formed. Thefabricating method of the transflective thin film transistor substratewith such a structure is as follows.

FIGS. 21A to 21E are sectional diagrams illustrating a method offabricating a transflective thin film transistor substrate shown in FIG.20. Referring to FIG. 21A, first a gate pattern, which includes a gateline 102, a gate electrode 108, a pixel electrode 118, and a data link136, is formed on a lower substrate 142 using a first mask process. Thegate pattern has a double layered structure including a transparentfirst conductive layer 101 and a second conductive layer 103. The firstmask process is the same as described in FIGS. 5A and 5B.

Then a gate insulating film 144, a semiconductor pattern 115 includingan active layer 114 and an ohmic contact layer 116, and a source/drainpattern including a data line 104, a source electrode 110, a drainelectrode 112, and a storage upper electrode 122 are formed using asecond mask process as illustrated in FIG. 21B. The second mask processis the same as described in FIGS. 6A and 7E.

Referring to FIG. 21C, a passivation film 146, which covers thesource/drain pattern, is formed using a third mask process, such thatthere is a transmission hole 154 in a transmissive area to expose afirst conductive layer of the pixel electrode, a third contact hole in acontact area to expose the side of the data line 104 by penetrating thedata line 104 and the semiconductor pattern 115, and a fourth contacthole 164 to expose the first conductive layer 101 of the data link 136.

Referring to FIG. 21D, an organic film 148 is formed on the passivationfilm 146 using a fourth mask process, such that the organic film 148 isremoved in the transmission hole 154 and the third and fourth contactholes 162, 164. Furthermore, the organic film 148 is opened in a padarea and it has an embossed surface only in the reflective area wherethe reflective electrode 152 is to be formed in the following process.The fourth mask process is the same as described in FIGS. 8A and 8B.

Referring to FIG. 21E, the reflective electrode 152 and a contactelectrode 160 are formed using a fifth mask process. The fifth maskprocess is the same as described in FIGS. 10A and 10B.

As described above, the transflective liquid crystal display device andfabricating method thereof according to the present invention connectsthe pixel electrode with the drain electrode and the storage upperelectrode using a reflective electrode that runs through the edge partof a transmission hole. Accordingly, the fabrication process of a thinfilm transistor substrate can be simplified to a five mask processesthereby reducing one mask process, and no separate contact hole isrequired to connect the pixel electrode with the drain electrode and thestorage upper electrode, thus the aperture ratio of the transmissivearea is increased.

Further, the transflective liquid crystal display device and a method offabricating same according to the present invention connects the datalink and the data line, which are formed in different layers, by use ofthe contact electrode of the same metal as the reflective electrode, andit reciprocally connects the thin film transistors of the electrostaticdischarging device. Accordingly, the fabrication process of a thin filmtransistor substrate can be simplified to five mask processes.

In addition, the transflective liquid crystal display device andfabricating method thereof according to the present invention has thereflective electrode AlNd connected to the first conductive layer ITOthrough the second conductive layer Mo of the pixel electrode, thus itcan reduce the contact resistance of the reflective electrode and thepixel electrode. Further, the reflective electrode is formed in thedouble structure of AlNd/Mo to enable to further reduce the contactresistance with the first conductive layer ITO of the pixel electrode.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A liquid crystal display device, comprising: a gate line including afirst transparent conductive layer; a first insulating film on the gateline; a data line crossing the gate line to define a pixel region, thepixel region having a transmissive area and a reflective area; a firstthin film transistor connected to the gate line and the data line; apixel electrode having a first transparent conductive layer; a storagecapacitor including a storage upper electrode overlapping the gate line;a transmission hole exposing at least a portion of the first transparentconductive layer of the pixel electrode; and a reflective electrodeformed in the reflective area of the pixel region, wherein thereflective electrode is directly connected with the pixel electrode, adrain electrode of the first thin film transistor and the storage upperelectrode within the transmission hole.
 2. The device according to claim1, further comprising a second conductive layer on the first transparentconductive layer of the gate line.
 3. The device according to claim 1,further comprising a second conductive layer on the boundary of thefirst transparent conductive layer of the pixel electrode.
 4. The deviceaccording to claim 2, further comprising: a double layered gate padextending from the gate line, wherein a portion of a first conductivelayer of the double layered gate pad is exposed via a first contact holeby passing through the first insulating film and a second conductivelayer of the double layered gate pad.
 5. The device according to claim4, further comprising: a double layered data pad connected to the dataline, wherein a portion of a first conductive layer of the doublelayered data pad is exposed via a second contact hole by passing throughthe gate insulating film and a second conductive layer of the doublelayered data pad.
 6. The device according to claim 5, further comprisinga second insulating film on the first thin film transistor.
 7. Thedevice according to claim 6, wherein the second insulating film isremoved in the gate and data pads.
 8. The device according to claim 6,further comprising a third insulating film between the first thin filmtransistor and the second insulating film.
 9. The device according toclaim 8, wherein the third insulating film is an inorganic insulatingmaterial.
 10. The device according to claim 6, further comprising athird insulating film between the second insulating film and thereflective electrode.
 11. The device according to claim 10, wherein thethird insulating film is an inorganic insulating material.
 12. Thedevice according to claim 3, wherein the reflective electrode isdirectly connected to the first transparent conductive layer of thepixel electrode and substantially laterally connected to the secondconductive layer of the pixel electrode through the transmission hole.13. The device according to claim 5, further comprising: a doublelayered data link extending from the data pad; and a first contactelectrode of the same metal as the reflective electrode connecting thedata line and the data line through third and fourth contact holesexposing the data line and the data link.
 14. The device according toclaim 13, further comprising an electrostatic discharging deviceconnected to one of the data and gate lines.
 15. The device according toclaim 14, wherein the electrostatic discharging device comprises: asecond thin film transistor connected to one of the gate and data lines;a third thin film transistor connected between a gate electrode and asource electrode of the second thin film transistor in a diode form; afourth thin film transistor connected between the gate electrode and adrain electrode of the second thin film transistor in a diode form; asecond contact electrode connected to a source electrode and a gateelectrode of the third thin film transistor through a fifth contact holeand a sixth contact hole exposing the source and gate electrodes; athird contact electrode connected to a drain electrode of the third orfourth thin film transistor and the gate electrode of the second thinfilm transistor through a seventh contact hole and a eighth contact holeexposing the drain and gate electrodes; and a fourth contact electrodeconnected to a source electrode and a gate electrode of the fourth thinfilm transistor through a ninth contact hole and a tenth contact holeexposing the source and gate electrodes of the fourth thin filmtransistor.
 16. The device according to claim 15, wherein the second,third and fourth contact electrodes are formed of the same metal as thereflective electrode.
 17. The device according to claim 15, wherein thegate electrodes have a double layered structure.
 18. The deviceaccording to claim 17, wherein the fourth, sixth, eighth, tenth contactholes expose a first conductive layer of the double layered structureelectrodes by passing through a second conductive layer of the gateelectrodes.
 19. The device according to claim 15, wherein the first tofourth contact electrodes are formed inner portion from a sealantregion.
 20. The device according to claim 15, wherein the reflectiveelectrode and the first to fourth contact electrodes are formed of AlNdand Mo.
 21. The device according to claim 6, wherein the insulating filmhas an embossed surface.
 22. The device according to claim 21, whereinthe reflective electrode has an embossed surface in a reflective area.23. The device according to claim 6, wherein the second insulating filmis an organic material.
 24. The device according to claim 1, wherein thestorage upper electrode substantially overlaps more than half of thegate line in the direction of the data line.
 25. The device according toclaim 1, wherein the reflective electrode connects the pixel electrodewith the thin film transistor and the storage upper electrode throughthe transmission hole.